1. Field of the Invention
The present invention relates generally to medical devices, and more particularly to medical devices intended for use within the body of an animal, and still more particularly to a stent and/or perfusion apparatus for selective intraluminal insertion and expansion. The apparatus of this invention provides an intraluminal stent that is, when used with a proper expansion device, selectively expandable, retractable and removable.
2. Description of the Prior Art
The use of stents as intraluminal expansion and perfusion apparatus is known to those of skill in the art. Many such devices are known as are the materials and methods for making them, and various apparatus useful in the placement of the stent in the lumen or vessel when desired.
U.S. Pat. No. 4,733,665, issued Mar. 29, 1988 to J. C. Palmaz describes an expandable stent for placement in the blood vessel of an animal. The Palmaz teaching is for a wire mesh stent that is expandable through use of an angioplasty balloon. The stent is to be used as a permanent graft.
U.S. Pat. No. 5,007,926 issued Apr. 16, 1991 to G. Derbyshire describes another stent adapted to be expanded by a balloon catheter. This stent includes ratchet means for allowing the selection of an expanded diameter for the stent. Derbyshire teaches that this stent is removable, but to do so the stent must be redilated to release the ratchet catch, and then a forceps is applied to remove the device.
U.S. Pat. No. 4,740,207, issued Apr. 26, 1988 to J. W. Kreamer also teaches a stent device selectively expandable by a balloon catheter which includes a retaining ledge on its inside wall that catches the edge of the expanding stent to hold it in a dilated position. There is no teaching in Kreamer of a means for retraction of the device once it has been dilated to a catch position.
U.S. Pat. Nos. 4,183,102, 4,693,249 and 4,877,030 all teach stent devices that are selectively expandable within a duct or vessel and which have some form of catch to hold in the expanded position. These devices are limited to a single catch expansion position and there are no means taught for the selective and simple removal of the stents.